textproduct: Quad Cities

KEY MESSAGES

- A Flood Watch remains in effect for areas south of Highway 20 through 10 AM this morning. Rainfall rates of 1-2 inches per hour at times will produce 1-3 inches of rain with localized areas of 3-5 inches possible (30-50%) north of I-80.

- A Dense Fog Advisory is in effect for the I-380 corridor and southeastern Iowa through 9 AM this morning. Visibility could drop to a quarter of a mile in some spots.

- The wet weather pattern will continue through the weekend with rounds of rain which may be heavy at times. There will be periods of dry weather between each round.

- The repeated rounds of rain will result in general rises on the Mississippi River with the potential for river flooding on tributary rivers. Refer to the hydrology section for more information.

SHORT TERM /THROUGH SATURDAY/

Issued at 316 AM CDT Thu Sep 17 2026

After a stormy start to the day, conditions are expected to improve by late morning after a mid-level trough passage. Rainfall totals between 1-3 inches are expected north of I-80 with latest CAM guidance having a low-to-medium chance (30-50%) of 3+ inches near and north of Highway 30. Dense fog also impacting the eastern outlook area this morning is expected to begin lifting between 8-9 AM. Northerly flow in the low- to- mid- levels will put a damper on shower coverage (10-20%) this afternoon compared to the last few days, and remnant cloud cover from last night's system should keep highs in the 70s areawide outside areas south of Highway 34 that could reach the mid-80s. Heading into tonight, winds are forecasted to shift back easterly ahead of an approaching warm front in association with surface cyclogenesis along the Front Range in Colorado. The WAA wing north of this boundary will produce scattered storms (50-70%) across eastern Iowa and northwest Illinois late tonight into Friday morning. The short duration of this round should limit the rain totals to less than inch (70-90% chance).

By Friday afternoon, the lobe of mid-level vorticity that spawned the Colorado low moves into the Upper Mississippi River Valley before being ejected eastward by the zonal flow. This drags the low pressure center northeastward towards Iowa. As the winds shift to out of the southeast, a warm, moist air is pulled northward into the CWA, setting the stage for another round of heavy rain north of I-80 Friday night into Saturday morning. Latest ensemble guidance shows a swath of 0.25-0.75 of an inch along the Highway 20 corridor (50-70% chance). The coverage and intensity of these storms will decrease throughout the day on Friday but remain scattered (40-60%) in nature along the Highway 20 corridor as the low pressure center drifts into northern Iowa.

LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/

Issued at 316 AM CDT Thu Sep 17 2026

Saturday night-Monday...A shortwave trough that has been camping across the western CONUS for most of the week will finally propagate eastward into the Northern Rockies Saturday night. Shortwave ridging over the Mid-to-Upper Mississippi River Valley introduces southwesterly flow aloft, pulling another mid-level vorticity lobe northward into the north-central Plains. This mid-level trough is forecasted to redevelop storms (50-70% coverage) along a cold front moving through the area. The SPC has a Marginal Risk, Level 1 out of 5, for most of the outlook area for isolated damaging winds, but the latest LREF guidance only has a 20-40% joint probability of SBCAPE exceeding 500 J/kg and the sfc-to-500 mb bulk shear exceeding 30 knots. Therefore, any convection that forms should struggle to organize.

After Saturday night, scattered PoPs (40-70%) will stick around into Monday as weak shortwaves rotating around the main trough axis, now over the Northern Plains, keeps CVA over the area. By Monday though, most precipitation will be in the form of rain showers as the boundary and low pressure over Missouri drifts further south and northeasterly flow from a high pressure over Ontario pumps in cooler air.

Tuesday-Wednesday...The shortwave trough over the Northern Plains finally reaches the Midwest on Tuesday. Isolated cold- core showers (20-30% coverage) could stick around during the day before subsidence sets in on the backside of the trough heading into Tuesday night and Wednesday. The persistent northeasterly flow should allow for seasonable temperatures with highs only in the mid-60s to low 70s (60-90% chance)!

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 642 AM CDT Thu Sep 17 2026

Variety of conditions across the TAF sites today. Tsra/shra activity will persist at DBQ through 15z, accompanied by MVFR/IFR vsbys and MVFR cigs. IFR cigs expected after 15z, gradually improving to low VFR by 00z. At CID, cigs will vary between MVFR/LIFR through 15z, becoming predominantly IFR between 15z-21z, then gradually improving to low VFR by 04z-06z. At MLI, LIFR cigs/IFR vsbys will improve to MVFR cigs/VFR vsbys by midday, then persisting through most of the TAF period, with MVFR fog possible after 08z. BRL lingers at the edge of VFR vs. LIFR cigs, but expect predominant MVFR cigs by 15z, then scattered VFR clouds by midday. MVFR clouds then expected to return after 00z, with MVFR vsbys possible after 08z. Light and variable winds will become northeast/east around 5kts at all but BRL, where south winds around 5 kts will gradually turn northwest then north by 00z.

HYDROLOGY

Issued at 231 PM CDT Wed Sep 16 2026

With a wet pattern expected to remain in place through the weekend and early next week, rising river levels are expected to occur.

Right now current forecasts and extended ensemble forecasts show within bank rises along the Mississippi with some areas approaching flood stage (10-20%). Area tributary rivers will also see rises. The Cedar, Iowa, Skunk and Wapsipinicon Rivers have a 20-40% chance of reaching flood stage over the next 10 days. The Green, Rock and Pecatonica Rivers have a 10-20% chance of reaching flood stage.

These probability are based on the current forecasted rainfall. If the rainfall is heavier/lighter or in a different location then the probabilities of the tributary rivers reaching flood stage with either increase or decrease.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Dense Fog Advisory until 9 AM CDT this morning for IAZ040-041- 051-052-063-064-076-077-087-088-098-099. Flood Watch until 10 AM CDT this morning for IAZ051>054- 063>068-076>078-087>089-098-099. IL...Flood Watch until 10 AM CDT this morning for ILZ007-009- 015>018-024>026. MO...Flood Watch until 10 AM CDT this morning for MOZ009-010.